demos: Update some of the WSI code to match the spec example code

A pending Vulkan spec change contains updates to the WSI example code.  This is
a coordinated, cosmetic change, that allows the example code and demo code to
more-closely match.

2 files changed, 56 insertions, 32 deletions

diff --git a/demos/cube.c b/demos/cube.c
index a7c5d868..6017444f 100644
--- a/demos/cube.c
+++ b/demos/cube.c
@@ -725,14 +725,13 @@ static void demo_draw(struct demo *demo) {
     VkPresentInfoKHR present = {
         .sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR,
         .pNext = NULL,
+        .waitSemaphoreCount = 1,
+        .pWaitSemaphores = &demo->draw_complete_semaphore,
         .swapchainCount = 1,
         .pSwapchains = &demo->swapchain,
         .pImageIndices = &demo->current_buffer,
-        .waitSemaphoreCount = 1,
-        .pWaitSemaphores = &demo->draw_complete_semaphore,
     };
 
-    // TBD/TODO: SHOULD THE "present" PARAMETER BE "const" IN THE HEADER?
     err = demo->fpQueuePresentKHR(demo->present_queue, &present);
     if (err == VK_ERROR_OUT_OF_DATE_KHR) {
         // demo->swapchain is out of date (e.g. the window was resized) and
@@ -768,12 +767,25 @@ static void demo_prepare_buffers(struct demo *demo) {
     assert(!err);
 
     VkExtent2D swapchainExtent;
-    // width and height are either both -1, or both not -1.
-    if (surfCapabilities.currentExtent.width == (uint32_t)-1) {
-        // If the surface size is undefined, the size is set to
-        // the size of the images requested.
+    // width and height are either both 0xFFFFFFFF, or both not 0xFFFFFFFF.
+    if (surfCapabilities.currentExtent.width == 0xFFFFFFFF) {
+        // If the surface size is undefined, the size is set to the size
+        // of the images requested, which must fit within the minimum and
+        // maximum values.
         swapchainExtent.width = demo->width;
         swapchainExtent.height = demo->height;
+
+        if (swapchainExtent.width < surfCapabilities.minImageExtent.width) {
+            swapchainExtent.width = surfCapabilities.minImageExtent.width;
+        } else if (swapchainExtent.width > surfCapabilities.maxImageExtent.width) {
+            swapchainExtent.width = surfCapabilities.maxImageExtent.width;
+        }
+        
+        if (swapchainExtent.height < surfCapabilities.minImageExtent.height) {
+            swapchainExtent.height = surfCapabilities.minImageExtent.height;
+        } else if (swapchainExtent.height > surfCapabilities.maxImageExtent.height) {
+            swapchainExtent.height = surfCapabilities.maxImageExtent.height;
+        }
     } else {
         // If the surface size is defined, the swap chain size must match
         swapchainExtent = surfCapabilities.currentExtent;
@@ -797,17 +809,16 @@ static void demo_prepare_buffers(struct demo *demo) {
         }
     }
 
-    // Determine the number of VkImage's to use in the swap chain (we desire to
-    // own only 1 image at a time, besides the images being displayed and
-    // queued for display):
-    uint32_t desiredNumberOfSwapchainImages =
-        surfCapabilities.minImageCount + 1;
-    // If maxImageCount is 0, we can ask for as many images as we want, otherwise
-    // we're limited to maxImageCount
+    // Determine the number of VkImage's to use in the swap chain.
+    // Application desires to only acquire 1 image at a time (which is
+    // "surfCapabilities.minImageCount").
+    uint32_t desiredNumOfSwapchainImages = surfCapabilities.minImageCount;
+    // If maxImageCount is 0, we can ask for as many images as we want;
+    // otherwise we're limited to maxImageCount
     if ((surfCapabilities.maxImageCount > 0) &&
-        (desiredNumberOfSwapchainImages > surfCapabilities.maxImageCount)) {
+        (desiredNumOfSwapchainImages > surfCapabilities.maxImageCount)) {
         // Application must settle for fewer images than desired:
-        desiredNumberOfSwapchainImages = surfCapabilities.maxImageCount;
+        desiredNumOfSwapchainImages = surfCapabilities.maxImageCount;
     }
 
     VkSurfaceTransformFlagsKHR preTransform;
@@ -822,7 +833,7 @@ static void demo_prepare_buffers(struct demo *demo) {
         .sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR,
         .pNext = NULL,
         .surface = demo->surface,
-        .minImageCount = desiredNumberOfSwapchainImages,
+        .minImageCount = desiredNumOfSwapchainImages,
         .imageFormat = demo->format,
         .imageColorSpace = demo->color_space,
         .imageExtent =
diff --git a/demos/tri.c b/demos/tri.c
index 9baa23a5..adfef501 100644
--- a/demos/tri.c
+++ b/demos/tri.c
@@ -587,14 +587,13 @@ static void demo_draw(struct demo *demo) {
     VkPresentInfoKHR present = {
         .sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR,
         .pNext = NULL,
+        .waitSemaphoreCount = 1,
+        .pWaitSemaphores = &drawCompleteSemaphore,
         .swapchainCount = 1,
         .pSwapchains = &demo->swapchain,
         .pImageIndices = &demo->current_buffer,
-        .waitSemaphoreCount = 1,
-        .pWaitSemaphores = &drawCompleteSemaphore,
     };
 
-    // TBD/TODO: SHOULD THE "present" PARAMETER BE "const" IN THE HEADER?
     err = demo->fpQueuePresentKHR(demo->queue, &present);
     if (err == VK_ERROR_OUT_OF_DATE_KHR) {
         // demo->swapchain is out of date (e.g. the window was resized) and
@@ -636,12 +635,25 @@ static void demo_prepare_buffers(struct demo *demo) {
     assert(!err);
 
     VkExtent2D swapchainExtent;
-    // width and height are either both -1, or both not -1.
-    if (surfCapabilities.currentExtent.width == (uint32_t)-1) {
-        // If the surface size is undefined, the size is set to
-        // the size of the images requested.
+    // width and height are either both 0xFFFFFFFF, or both not 0xFFFFFFFF.
+    if (surfCapabilities.currentExtent.width == 0xFFFFFFFF) {
+        // If the surface size is undefined, the size is set to the size
+        // of the images requested, which must fit within the minimum and
+        // maximum values.
         swapchainExtent.width = demo->width;
         swapchainExtent.height = demo->height;
+
+        if (swapchainExtent.width < surfCapabilities.minImageExtent.width) {
+            swapchainExtent.width = surfCapabilities.minImageExtent.width;
+        } else if (swapchainExtent.width > surfCapabilities.maxImageExtent.width) {
+            swapchainExtent.width = surfCapabilities.maxImageExtent.width;
+        }
+        
+        if (swapchainExtent.height < surfCapabilities.minImageExtent.height) {
+            swapchainExtent.height = surfCapabilities.minImageExtent.height;
+        } else if (swapchainExtent.height > surfCapabilities.maxImageExtent.height) {
+            swapchainExtent.height = surfCapabilities.maxImageExtent.height;
+        }
     } else {
         // If the surface size is defined, the swap chain size must match
         swapchainExtent = surfCapabilities.currentExtent;
@@ -651,15 +663,16 @@ static void demo_prepare_buffers(struct demo *demo) {
 
     VkPresentModeKHR swapchainPresentMode = VK_PRESENT_MODE_FIFO_KHR;
 
-    // Determine the number of VkImage's to use in the swap chain (we desire to
-    // own only 1 image at a time, besides the images being displayed and
-    // queued for display):
-    uint32_t desiredNumberOfSwapchainImages =
-        surfCapabilities.minImageCount + 1;
+    // Determine the number of VkImage's to use in the swap chain.
+    // Application desires to only acquire 1 image at a time (which is
+    // "surfCapabilities.minImageCount").
+    uint32_t desiredNumOfSwapchainImages = surfCapabilities.minImageCount;
+    // If maxImageCount is 0, we can ask for as many images as we want;
+    // otherwise we're limited to maxImageCount
     if ((surfCapabilities.maxImageCount > 0) &&
-        (desiredNumberOfSwapchainImages > surfCapabilities.maxImageCount)) {
+        (desiredNumOfSwapchainImages > surfCapabilities.maxImageCount)) {
         // Application must settle for fewer images than desired:
-        desiredNumberOfSwapchainImages = surfCapabilities.maxImageCount;
+        desiredNumOfSwapchainImages = surfCapabilities.maxImageCount;
     }
 
     VkSurfaceTransformFlagsKHR preTransform;
@@ -674,7 +687,7 @@ static void demo_prepare_buffers(struct demo *demo) {
         .sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR,
         .pNext = NULL,
         .surface = demo->surface,
-        .minImageCount = desiredNumberOfSwapchainImages,
+        .minImageCount = desiredNumOfSwapchainImages,
         .imageFormat = demo->format,
         .imageColorSpace = demo->color_space,
         .imageExtent =